For years, Sandor Katz has been fermenting foods, convinced that the probiotics they contain are keeping him healthy despite his compromised immune system.

What’s more, says Katz, fermented raw vegetables (as well as other cultured foods, such as yogurt and kefir, or fermented milk) offer unique health benefits by infusing the gut with healthy bacteria and also by increasing the bioavailability of minerals and vitamins. “As fermentation progresses, it creates lactic acid,” explains Mingruo Guo, Ph.D., a professor in the University of Vermont’s Department of Nutrition and Food Sciences. “This makes minerals more soluble.

It also produces enzymes that help break down proteins and fatty acids, which can help digestion.”

Clinical evidence supporting the health benefits of probiotics—particularly in supplement form—is mounting. For example, a study published in the journal Pediatrics last spring showed that taking probiotic supplements can reduce fever incidence due to colds and flu in children by nearly 73 percent. That’s all well and good, but as Katz says, “Why would you pay a lot of money to get your nutrients in a [supplement], when you can get them in your food for next to nothing?”

But are fermented vegetables (uncooked, unrefrigerated) safe? “I truly believe that fermented vegetables are safer than raw,” says Katz, who ferments his kimchi in a 55-gallon wooden barrel that once contained Jack Daniels. “You’re creating a competitive situation that protects you from pathogens, so even if you ended up fermenting a cabbage leaf that had E. coli on it, the good bacteria would overwhelm the bad and you’d never get sick.” A bit of an oversimplification, says food-safety expert Douglas L. Archer, Ph.D., associate dean for research at the Institute of Food and Agricultural Sciences at the University of Florida in Gainesville. “E. coli 0157:H7, as well as the Salmonella family of bacteria, are quite stable in acidic environments,” says Archer. “While fermenting may lessen the chance of illness, it is not foolproof.”